Transcript for Chad Vaccarino of 'A Great Big World' Discusses Health, Personal Life

We're going to kick off requested the "Gma heat index."" one of the members of the duo, a great big world, has opened up about a medical condition he's kept secret for years. Juju Chang has that story. ? I'm sorry I couldn't get to you ? Reporter: He's half of the dynamic duo behind one of the biggest pop hits of the year. ? Say something I'm giving up on you ? Reporter: Now, Chad Vaccarino is saying something about his serious health condition. In 2007, I was diagnosed with multip multip multiple sclerosis. I was experiencing buckling of my legs. Vertigo. Reporter: You weren't nervous coming forward and talking about your disease. It's a big thing to put out there to the universe and the world. Reporter: Vaccarino says he was diagnosed in college. And tried weekly injections of medication. What was the traditional treatment like? I would get sick the next day. And I started experiencing seizures from these drugs. Reporter: But it was this video, a Ted talk by Dr. Terry walls that Vaccarino says turned his life around. A medical doctor with Progressive M.S., once wheelchair-bound, changed the way she sate and says she got better. Three months later, I could walk between the exam rooms using one cane. Reporter: Vaccarino immediately took her advice, by following the Paleo diet. Eating only foods that can be hunted and gathered. And eliminating dairy and processed foods. Did your M.S. Symptoms go away? Went away. Completely. It was the diet. Reporter: There is some data about a change in diet, helping the disease, it is spores. There's no evidence that changing one's diet can change the course of multiple sclerosis. Reporter: But Vaccarino says, he never felt better. And he hopes by sharing his story, he can help others. Chad says Dr. Walls is currently trying to raise funding for clinical trials based on her protoc protocol. But it's part of people using the Paleo diet, worried about health. He is symptom-free? He is absolutely symptom-free. And he says how amazing. Next up, "Wall Street journal" piece getting a lot of

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